An analysis of the costs and benefits of the cyanogenic system in Trifolium repens L.

Abstract

The effect of the cyanogenic glucosides linamarin and lotaustralin and their hydrolyzing enzyme linamarase was studied in a B2 generation segregating for the genes Ac and Li. Plants containing the glucosides are protected against grazing by snails both in the seedling stage and as adult plants. In seedlings, however, there is a direct effect on survival, whereas in adult plants the leaf area of plants containing linamarin/lotaustralin is less reduced under intense grazing. Linamarase has no effect on grazing by snails, possibly as a result of the presence of β-glucosidase activity in the gut of these animals. The genes Ac and Li, or genes tightly linked to them, have other effects as well: plants possessing one dominant Ac allele produce fewer flowers than homozygous ac plants. I compared this difference in flower production to the metabolic cost of producing the cyanogenic glucosides. The energy content of the difference in flower head production far exceeded the metabolic cost of cyanoglucoside production in Acac plants. It is possible that the cost of maintaining a certain level of cyanoglucosides is much more important for the plant than the initial cost of biosynthesis. The importance of the effects of Ac and Li in the maintenance of cyanogenic polymorphism in white clover is discussed.

Testing trade‐offs among growth, regrowth and anti‐herbivore defences in Senecio jacobaea*

“…In theory a trade-off is expected between growth/seed production and defence, as was indeed found in some studies (Coley, 1986;Kakes, 1989;Baldwin et al, 1990). In many other cases, however, no such trade-off was found (Brown, 1988;Simms & Rausher, 1987;Briggs & Schultz, 1990).…”

Plant Cyanogenesis of Phaseolus lunatus and its Relevance for Herbivore–Plant Interaction: The Importance of Quantitative Data

“…Furthermore, cyanogenesis seems to be beneficial for plants under specific environmental conditions (Kakes, 1989). The distribution of cyanogenesis in populations of Lotus corniculatus L. and Trifolium repens L. depends on abiotic factors that are also determining the occurrence and activity of snails, the important herbivores of clover (Jones, 1966(Jones, , 1972(Jones, , 1988.…”

Searching for the bull’s eye: agents and targets of selection vary among geographically disparate cyanogenesis clines in white clover (Trifolium repens L.)

“…In many studies, cyanogenesis has been found to be an effective deterrent against generalist clover herbivores, including slugs and snails (for example, see Angseesing, 1974;Dirzo and Harper, 1982a, b;Kakes, 1989), insects (Dritschilo et al, 1979;Pederson and Brink, 1998) and small mammals (Saucy et al, 1999;Viette et al, 2000). These findings suggest that cyanogenesis is adaptive in the presence of herbivores.…”

“…These findings suggest that cyanogenesis is adaptive in the presence of herbivores. At the same time, cyanogenesis appears to be energetically costly and disadvantageous in environments with low herbivore pressure; acyanogenic cyanotypes tend to show greater flower production than cyanogenic plants in the absence of herbivores, suggesting a selective advantage for acyanogenic plants under these conditions (Kakes, 1989). These two agents of selection-herbivore pressure and energetic costs of cyanogenesis-could together account for the observed clinal variation if cooler climates are characterized by lower herbivore abundance or shorter periods of herbivory, a pattern that has been observed in other temperate ecosystems (for example, see Pennings and Silliman, 2005).…”

“…A leading hypothesis has been that a fitness tradeoff occurs whereby cyanogenic plants have an advantage in warmer locations, where herbivore pressure is high, but are at a competitive disadvantage in cooler, low-herbivory environments because of the energetic costs of producing cyanogenic components (Kakes, 1989). However, there is also evidence that herbivore pressure may not be the sole factor driving cyanogenesis cline evolution.…”